Oh, that's different, even though I could not see the utility, my wireless still worked post upgrade. There may be a more elegant solution, but this is all I know:
* do a hard reset on whichever TC or AE is your main unit (ideally the one connected directly to the Mac)
* after its hard reset, it *should* come up in the utility ... make sure it is firmware updated, set it up as desired and make sure both wired and wireless work off of it
* do a hard reset on your 2nd device, wait for it to come up and then repeat the steps to use this device to extend the network (that's what I'm assuming your setup was)
Good luck.